Application of superabsorbent polymers (SAP) as desiccants to dry maize and reduce aflatoxin contamination

Effect of humidity on aflatoxin contamination for selected African leafy vegetables

In this study, the aflatoxin contamination level of selected freshly harvested and dried African leafy vegetables was investigated after inoculation with Aspergillus flavus spores and incubation at 32%, 74%, 84%, and 96% static relative humidity. The study question was whether Aspergillus sp. growth on selected vegetables: Corchorus olitorius, Crotalaria ochroleuca, Vigna unguiculata, Solanum villosum, and Amaranthus blitum can produce aflatoxins. The experiment was replicated thrice and a control sample was included for each replicate. An Agilent 1260 Infinity HPLC system was used for analysis and we quantified the following aflatoxins; B1, B2, G1, and G2 in the selected vegetables. Our results show that aflatoxin B1, G1, and G2 were all present, with the B1 being prevalent. The contamination level increased with relative humidity increase for both freshly harvested and dried vegetables. However, the dried vegetables had a lower contamination level in comparison with freshly harvested. The findings affirm the importance of post-harvest crop preservation to avoid mycotoxin contamination. The vegetables can suffer aflatoxin contamination when exposed to high moisture and ambient temperature and drying is a suitable method of vegetable preservation.

Preserving the food preservation legacy

This paper deals with the question about how early humans managed to feed themselves, and how they preserved and stored food for times of need. It attempts to show how humans interacted with their environments and demonstrate what lessons can be learnt from the about 3.4 million years of food processing and preservation. It includes a discussion about how hominins shifted from consumption of nuts and berries toward meat and learnt to control and use fire. Cooking with fire generated more food-related energy and enabled humans to have more mobility. The main trust of the paper is on historical food preservations, organized from the perspectives of key mechanical, thermal, biological and chemical processes. Emerging food processes are also highlighted. Furthermore, how humans historically dealt with food storage and packaging and how early humans interacted with their given environments are discussed. Learnings from the history of food preservation and culinary practices of our ancestors provide us with an understanding of their culture and how they adapted and lived with their given environments to ensure adequacy of food supply. Collaboration between food scientists and anthropologists is advocated as this adds another dimension to building resilient and sustainable food systems for the future.

Drying of African leafy vegetables for their effective preservation: the difference in moisture sorption isotherms explained by their microstructure

The problem of malnutrition and nutrition deficiency, as well as droughts that lead to reduction in food supply and starvation, is well documented for Sub-Saharan Africa. Reducing post-harvest losses of five species of African leafy vegetables (ALVs) by preservation through drying is studied herein. Energy efficient gentle drying conditions using superabsorbent polymers and a temperature of 40 °C were shown to preserve most leaf structures and vitamins. The microbial safe moisture content of the ALVs was found to be ≤14% dry basis. Dried Slender Leaf and Nightshade leaves could be rehydrated to the equilibrium moisture content of fresh leaves upon dry storage, while it was not possible for Jute Mallow, Cowpea and Amaranthus. This was attributed to different palisade parenchyma cell lengths. An increased amount of starch granules as observed in the microstructure of Cowpea and Nightshade leaves is suggested to explain their fibrous texture upon cooking. These results show that the ALVs can be effectively preserved using the same drying method and that this can be used to fight micro-nutrient deficiencies during droughts.

Influence of socio-economic and agronomic factors on aflatoxin and fumonisin contamination of maize in western Kenya

Consumption of maize contaminated with mycotoxins has been associated with detrimental health effects. A farm survey covering 116 push-pull and 139 non-push-pull cropping systems was conducted to determine the socio-economic and agronomic factors that influence farmers' knowledge on incidence and contamination of maize by ear rots and associated mycotoxins in western Kenya. All the respondents were smallholder farmers between the ages of 23 and 80 years, with 50% of them being female. Maize samples were collected from the standing crop in the field of each interviewed farmer and analyzed for aflatoxin and fumonisin. Only a small proportion of farmers had knowledge of aflatoxin and ear rots in maize. Overall, less than 20% of maize samples were contaminated with both aflatoxin and fumonisin, and more maize samples were contaminated with fumonisin as compared to aflatoxin. Proportions of maize samples containing higher than the acceptable Kenyan regulatory threshold (10 µg/kg) for aflatoxin and European Commission regulatory threshold (1,000) µg/kg for fumonisin were lower in maize samples from push-pull cropping system. Age of farmer and county of residence were significantly and positively associated with knowledge of aflatoxin, while cropping system, county of residence, and level of education were positively associated with knowledge of maize ear rots. There was strong correlation between knowledge of maize ear rots and knowledge of aflatoxin. Levels of both aflatoxin and fumonisin were significantly and positively associated with the use of diammonium phosphate (DAP) fertilizer at planting. Aflatoxin levels were also positively associated with stemborer damage. Agronomic practices were not significantly different between push-pull and non-push-pull farmers. However, use of DAP fertilizer was the most important agronomic factor since it was associated with both aflatoxin and fumonisin contamination of maize. These results imply that creating awareness is key to mitigation of ear rots and mycotoxin contamination of maize. The results also suggest that the levels of aflatoxin and fumonisin in maize in western Kenya were influenced both by pre-harvest agronomic practices and by the cropping system adopted, push-pull or not.

Prevalence and mitigation of aflatoxins in Kenya (1960-to date)

Aflatoxins are highly toxic metabolites of several Aspergillus species widely distributed throughout the environment. These toxins have adverse effects on humans and livestock at a few micrograms per kilogram (μg/kg) concentrations. Strict regulations on the concentrations of aflatoxins allowed in food and feed exist in many nations in the developing world. Loopholes in implementing regulations result in the consumption of dangerous concentrations of aflatoxins. In Kenya, where 'farm-to-mouth' crops become severely contaminated, solutions to the aflatoxins problem are needed. Across the decades, aflatoxins have repeatedly caused loss of human and animal life. A prerequisite to developing viable solutions for managing aflatoxins is understanding the geographical distribution and severity of food and feed contamination, and the impact on lives. This review discusses the scope of the aflatoxins problem and management efforts by various players in Kenya. Economic drivers likely to influence the choice of aflatoxins management options include historical adverse health effects on humans and animals, cost of intervention for mitigation of aflatoxins, knowledge about aflatoxins and their impact, incentives for aflatoxins safe food and intended scope of use of interventions. It also highlights knowledge gaps that can direct future management efforts. These include: sparse documented information on human exposure; few robust tools to accurately measure economic impact in widely unstructured value chains; lack of long-term impact studies on benefits of aflatoxins mitigation; inadequate sampling mechanisms in smallholder farms and grain holding stores/containers; overlooking social learning networks in technology uptake and lack of in-depth studies on an array of aflatoxins control measures followed in households. The review proposes improved linkages between agriculture, nutrition and health sectors to address aflatoxins contamination better. Sustained public awareness at all levels, capacity building and aflatoxins related policies are necessary to support management initiatives.

Active Packaging Applications for Food

The traditional role of food packaging is continuing to evolve in response to changing market needs. Current drivers such as consumer's demand for safer, "healthier," and higher-quality foods, ideally with a long shelf-life; the demand for convenient and transparent packaging, and the preference for more sustainable packaging materials, have led to the development of new packaging technologies, such as active packaging (AP). As defined in the European regulation (EC) No 450/2009, AP systems are designed to "deliberately incorporate components that would release or absorb substances into or from the packaged food or the environment surrounding the food." Active packaging materials are thereby "intended to extend the shelf-life or to maintain or improve the condition of packaged food." Although extensive research on AP technologies is being undertaken, many of these technologies have not yet been implemented successfully in commercial food packaging systems. Broad communication of their benefits in food product applications will facilitate the successful development and market introduction. In this review, an overview of AP technologies, such as antimicrobial, antioxidant or carbon dioxide-releasing systems, and systems absorbing oxygen, moisture or ethylene, is provided, and, in particular, scientific publications illustrating the benefits of such technologies for specific food products are reviewed. Furthermore, the challenges in applying such AP technologies to food systems and the anticipated direction of future developments are discussed. This review will provide food and packaging scientists with a thorough understanding of the benefits of AP technologies when applied to specific foods and hence can assist in accelerating commercial adoption.